Disposable surgical safety scalpel

ABSTRACT

A disposable surgical safety scalpel (3) with a retractable blade that can be retracted inside a protective shell (5); return of the blade into the shell (5) is operated through an elastic return means (15), acting between a blade support (4) and said shell (5). Movement of the support (4) and thus of the blade (3) is effected by operating a pivoted button (13), facing through a window (11) of the shell (5), said pivoted button (13) being provided with an automatic lock for the blade in said retracted position in the shell (5) and a voluntary lock for the blade in the position for use.

The present invention relates to a disposable surgical safety scalpelfor medical use, having a retractable blade.

A scalpel is a highly professional surgical instrument which has beenperfected over the years to such an extent that it cannot be compared toa jack knife or a cutter.

In describing the state of the art, reference can be made only from anhistorical viewpoint to some patents relating to knives described in themore or less recent past, whose characteristic was to have a blade thatis positioned after use in a protective container.

This is the case, for example, of the following patents:

GB-5487 (LAKE), which as far back as 1884 described a knife with anextractable blade;

U.S. Pat. No. 4,028,758 (O'CONNOR), which describes a combination of autility knife and a staple remover;

U.K. 1511889 (STEABBEN), which describes a pocket cutter with a bladethat retracts but not automatically;

U.S. Pat. No. 4,769,912 (DAVIS), which describes a knife with anacceleration sensor;

U.S. Pat. No. 4,858,320 (LEMAIRE), which describes a pocket knife withretractable blade;

DE-3735294 (TEIHS), U.S. Pat. No. 4,835,865 (KNOOP) and lastlyBE.1.002.554 (VAN HOOYDONCK), which describe an industrial cutter withretractable blade.

As is well known, the surgical scalpels existing on the market are ofthe disposable or reusable type, with a fixed or interchangeable blade,and do not normally have any protection, except for a blade protectingcap in the case of disposable scalpels, which cap is slipped off beforeuse and could be replaced after use.

In fact the cap should never be replaced because this maneuver can causeunwelcome cuts, with the risk of transmission of diseases, includingserious ones like AIDS and viral hepatitis.

The use of a barrier system, such as gloves with a steel mesh, whichprotect from cuts but not from stab wounds, is not well accepted becauseof the increased thickness and stiffness of the gloves, which leads to aloss of sensitivity.

The use of a different system, called "Magnetic Drape", which consistsof a sort of magnet cloth to be placed near the operating field and towhich the surgical instruments adhere through the action of a magnet,avoids the stage of passing the instruments from hand to hand, thuseliminating some wounds, i.e. those that occur during exchange ofinstruments between operators.

This system is poorly received by surgeons because it is essential tolook away from the operating field to grasp the instrument and alsobecause it is of no use for non-metallic objects.

The majority of accidental scalpel stab wounds or cuts occurs not somuch when the surgeon makes an incision in the patient's skin or tissueas when the scalpel is passed from hand to hand by the medical operatorsor during disposal.

A study published in the USA in April 1995 by Dr. Janine Jagger in"Advances in exposure prevention", Volume 1 No. 3 published by"INTERNATIONAL HEALTH CARE WORKER SAFETY RESEARCH AND RESOURCE CENTER"showed that 34% of scalpel wounds occur during use of the instrument,whilst the remaining 39% and 27%, respectively, take place when thescalpel is passed from hand to hand by operators and duringremoval-replacement-disposal of the blade.

From these data it emerges that, overall, scalpels with an exposed bladeor an interchangeable blade are responsible for 66% of cut wounds thatoccur among medical operators before, during and after use of theinstrument.

It is for this reason that all scalpels with an exposed blade, such asthose currently on the market must be considered dangerous, as well asthose with an interchangeable blade, such as those forming the object ofthe following patents:

PCT-WO 90/11725 (DOLGIN), which describes a metal scalpel with a mobileguard, with no automatic return and requiring replacement of the blade;

U.S. Pat. No. 5,250,063 (ABIDIN), which describes a metal scalpel with amobile guard and an interchangeable blade;

PCT-WO 94/13216 (WERNER), which describes a metal scalpel with avoluntarily or automatically retracting blade that is extremelydangerous in that pressure exerted on the rear part causes an accidentalforward movement of the blade, is difficult to construct and also has aninterchangeable blade;

PCT-WO 95/15723 (GHARIBIAN), which describes a scalpel with a mobileguard and interchangeable blade without any locking system between thecap and the blade holder, making it difficult to use and dangerous;

PCT-WO 93/24064 (NEWMAN P. H.) and U.S. Pat. No. 5,403,337 (PLATTS)which describe a disposable scalpel with a blade that can be changedduring the surgical procedure, without foreseeing any protection forused blades.

Changing of the blade is in fact the weak point of any instrument, eventhose considered safe, because handling necessarily leads to anincreased risk of accidental wounds.

In the analysis of the state of the art it can be seen that as time wenton inventors refined the idea of a safe scalpel to meet the need forprotection required by surgeons.

Starting from mobile blade protection systems without automatic return,such as, for example, those described in patents:

U.S. Pat. No. 3,905,101 (SHEPHERD), U.S. Pat. No. 3,906,626 (RIULI),U.S. Pat. No. 4,414,974 (DOTSON), EP-0 251 485 (GORDY), U.S. Pat. No.4,735,202 (WILLIAMS), EP-0 612 506 (NEWMAN C. D.),

whose main defects lie in the need to use both hands to set up or toprotect the instrument and the necessity to remember to cover the bladeeach time it is passed from hand to hand, systems have been designedwith a mobile blade guard that can be moved with only one hand, butstill without automatic return of the cap, such as those described inpatents:

PCT-WO 90/11725 (DOLGIN), U.S. Pat. No. 5,250,063 (ABIDIN), U.S. Pat.No. 5,417,704 (WONDERLEY), PCT-WO 95/15723 (GHARIBIAN),

in which advancement and retraction of the protective cap is carried outwith one hand and must be intentional on the part of the operator.

Again with regard to mobile guard, the following patents must beconsidered separately:

U.S. Pat. No. 5,330,492 (HAUGEN), which describes a scalpel with a guardthat can be moved by means of a push-button, which when pressed causesthe protective cap to retract, uncovering the blade, and when releasedunintentionally causes the opposite effect; this instrument must begrasped in a an unnatural way, does not offer guarantees of safetybecause the push-button protrudes excessively and in addition, becauseof its excessive height, does not allow a correct cutting angle on theskin surface;

U.S. Pat. No. 5,330,494 (VAN DER WESTHUIZEN), which describes a guardthat can move transversely to the blade, constituting a danger not onlyfor the operators, because pressure exerted casually on the lower edgeof the cap causes uncovering of the blade with a high risk of wounds,but also for patients since the cutting force cannot be regulated.

More recently different systems have been proposed, such as, forexample, that in U.S. Pat. No. 5,116,351 (FRASSETTI), which describes amobile blade mechanism, with automatic return of the blade to theprotected position and with the possibility of voluntary locking, but isbasically awkward because it obliges the operator to work in anunnatural position, that is with the finger exerting a certain pressureon the upper edge of the blade and with the blade partly covered by theprotection system; and that of U.S. Pat. No. 5,207,696 (MATWIJCOW),which describes a scalpel with a retractable blade and mobile guard, butwhich seems too bulky and therefore awkward and has no automaticinvoluntary return of the blade to the covered position.

A further development in the design of these instruments has come aboutwith a concept that foresees the possibility of extracting the bladefrom the handle. This is probably the idea that holds most advantagesbecause it offers interesting solutions to the problems described up tonow, although each of the ideas proposed gives rise to someconsiderations as regards their practical operation.

A first proposal for a retractable blade is presented in:

EP-0 217 638 (DESATNICK), which describes an instrument for closedcavity surgery, with a small retractable blade, without automaticreturn, not disposable, therefore dangerous during blade changes, andnot suitable for skin incisions;

PCT-WO 93/24064 (NEWMAN P. H.), which describes a scalpel with lockingof the exposed blade, which is very difficult to set up, with voluntaryreturn, with the risk of the blade holder with the blade coming outaccidentally from the rear part of the cover, without any protectionagainst an accidental forward movement of the blade and with thepossibility of replacing the blades during a surgical procedure, anoperation which seems dangerous because the exposed blade is handled;

U.S. Pat. No. 5,330,493 (HAINING) which describes a disposable scalpelwith a retractable blade, without automatic return of the blade to theresting position, with a button for forward movement of the blade thatis situated on its upper edge and is therefore awkward to slide, andwith a permanent end-of-use lock, which seems superfluous and couldsometimes be applied accidentally, thus making it impossible to use theinstrument;

PCT-WO-94/13216 (WERNER), which describes a metal scalpel with voluntaryautomatic retraction of the blade that is extremely dangerous because ifpressure exerted on its rear part causes an accidental unintentionalforward movement of the blade, that is difficult to construct and alsohas an interchangeable blade;

PCT-WO-95/15122 (WERNER) is different from the preceeding one for theuse of a different system of locking of the blade in an operativeposition.

U.S. Pat. No. 5,344,424 (ROBERTS) which presents a disposable scalpelwith voluntary retraction, with three locking positions, i.e. anoperative or set up position, an inoperative position and a safetyposition, where the only innovation appears to be the internal safetydevice, but which is difficult to handle and dangerous because the bladeadvance system protrudes too far;

EP-0 622 047 (DERBYSHIRE), which describes an original blade advancesystem in which pressure is exerted on a flexible container (balloon),with automatic spring-operated return, with the defect that seeing theblade retract each time pressure is exerted on skin or tissues becauseof the intrinsic elasticity of the balloon itself, and the blade canaccidentally move forward through unintentional pressure exerted byother instruments or hands;

U.S. Pat. No. 5,403,337 (PLATTS), which describes a scalpel whollysimilar to the one described in PCT-WO 93/24064 (NEWMAN P. H.),criticizing it as awkward and dangerous and adding its own smallmodification to eliminate these defects, but making it more difficult toset up with only one hand (the rear part of the handle has been widenedto allow for positioning of two stops) and still foreseeing bladechanges during the surgical procedure, which continues to represent ahazard;

U.S. Pat. No. 5,431,672 (COTE), which presents a scalpel with automaticvoluntary return of the blade with an additional internal lock, whichcould be accidentally applied during surgical procedures, forcing themedical staff to use a new scalpel; the voluntary locking of the bladein the operative position is complicated and unconfortable to be engagedand disengaged and require the use of both the hands.

PCT-WO-95/24855 (DILLON), which shows a scalpel with automatic,voluntary blade return, with an unsafe stopping system for the exposedblade and with locking devices not better identified to avoid re-use;

PCT-WO 93/25152 (FLUMENE et al.), which presents a disposable scalpelwith rear lock to prevent any accidental forward movement of the blade,with easy blade exposure, without any locking in the operative or set upposition of the blade, so as to have automatic, involuntary return andlocking in the resting position; moreover, a particular characteristicis the possibility of graduating extraction of the blade according tothe type of incision, always acting on the instrument in a comfortable,ergonomic position; the only drawback to be noted is that since it doesnot have a forward lock use of this instrument is rather awkward in someoperating conditions, so the presence of a stop device for the blade inoperative position could be desirable in some circumstances.

The aim of this invention is, therefore, to solve some of the problemsposed by the prior art.

In particular, an aim of the invention is to provide a scalpel that issafe when passed among the operators, protected during transport anddisposal of used materials and offers different possibilities of use, sothat it is accepted by virtually all users, irrespective of theirpreferences for handling of the instrument.

Another aim of the invention is to provide safety locks for the bladethat can easily be removed by moving one finger of the hand holding thescalpel, which is the same finger used to advance the blade.

Yet another aim of the invention is to provide a protected scalpel ofthe above type that is easy to construct, automatically assemblable andeconomical.

A surgical safety scalpel in accordance with the invention ischaracterized by the characteristics listed in appended independentclaim 1.

Advantageous embodiments of the invention are described in the dependentclaims.

Essentially, the scalpel according to the invention is provided with avoluntary locking means for intentionally locking the blade in positionfor use, which the operator can operate or not, depending on how heprefers to work.

If this locking means is operated, it must be disabled after use toallow return of the blade.

This manoeuvre is extremely simple, however, and does not requireparticular care on the part of the user.

An advantage of the present invention lies in the presence of anautomatic lock which operates at the end of a run retraction of theblade, thus avoiding an accidental emerging of the same.

Another advantage of the present invention therefore lies in the factthat the manoeuvres made on the scalpel (releasing the rearlock--advancing the blade--inserting and releasing the front lock whenrequired) are effected by means of a single finger of a same hand,keeping the scalpel in its correct use position and leaving the otherhand free to make another action.

The use of a single hand and the fact that there is no necessity to takethe eyes off the operation field make it possible for the surgeon'sprocedure not to be modified, representing therefore a further reasonwhy this safe device can be well accepted by the medical class.

Further characteristics of the invention will be made clearer from thedetailed description given below, referring to, one of its purelyexemplary and therefore non-limiting embodiments, illustrated in theappended drawings, in which:

FIG. 1 is a top plan view of a scalpel according to the invention, in afirst embodiment, with the blade retracted inside the shell, in aninoperative position;

FIG. 2 is a median section, taken along the line II--II in FIG. 1;

FIG. 3 is a top plan view of the scalpel in FIG. 1, with the blade inposition for use;

FIG. 4 is a median section taken along the line IV--IV in FIG. 3, andshows that the voluntary blade lock has not been applied;

FIG. 5 is a top plan view of the scalpel in FIG. 1, with the bladeextracted, in the operating position, as in FIG. 3;

FIG. 6 is a median section taken along the line VI--VI in FIG. 5, andshows voluntary locking of the blade in said operating position;

FIG. 7 is a plan view of a support-slider of a scalpel in accordancewith an embodiment of the invention;

FIG. 7A is a side view of the support in FIG. 7;

FIGS. 7B, 7C, 7D are sections taken along the planes B--B, C--C andD--D, respectively, in FIG. 7;

FIG. 8 is a plan view, in partial section, of a half-shell able toaccommodate the support in FIG. 7;

FIG. 8A is a side view, in partial section, of the half-shell in FIG. 8;

FIG. 9 is a plan view, in partial section, of a second half-shell,suitable for coupling to the half-shell in FIG. 8;

FIG. 9A is a part-sectional side view of the half-shell in FIG. 9;

FIG. 9B is a front view taken in the direction of the arrow F in FIG. 9;

FIG. 9C is a section taken along the plane C--C in FIG. 9.

With reference to the appended figures, and for now to FIGS. 1-6 inparticular, a safety scalpel according to a first embodiment of theinvention has been indicated as whole with reference number 1. Itcomprises a scalpel proper 2, consisting of a blade 3 and an elongatedsupport 4 and a shell or outer case 5, acting as a handle, made in twohalves or half-shells 6, 7, joined together by mortising or assembled inanother way, for example by welding.

The scalpel 2 is housed inside the shell 5, which has one end 8 closedand the opposite end 9 open, and has the possibility of slidinglongitudinally, in such a way that the blade 3 can be brought from aresting or inoperative position in which it is housed completely insidethe shell 5 (FIGS. 1 and 2), to an operative position or position foruse, in which it projects from the open end 9 of the shell 5 (FIGS.3-6).

The elongated support 4 of the blade 3 acts as a slider and is guidedbetween the side walls 10 of the shell 5. In the upper half orhalf-shell 7 a longitudinal aperture or window 11 is foreseen, with asubstantially rectangular shape, with a narrowing 12 at the front, onthe side where the blade 3 is positioned. A push-button or pivotedbutton 13 of the support 4 appears in the window 11, protruding onlyslightly from the window 11, the operator being able to operate saidbutton with one finger to cause the support-slider 4 to slide. To makethe button easier to grip, normally with the thumb, transverse ribs 14are provided on it.

The support 4 is held in its retracted position when it is housed insidethe shell 5 by an elastic means, in particular by a tensile spring 15operating between a small pin 16 projecting downward from the support 4and a small pin 17 projecting downward from the upper half-shell 7, inthe vicinity of the closed end 8 of the shell 5.

The pivoted or oscillating button 13 pivots on a pin 18, disposedtransversely to the support 4, between a pair of vertical, longitudinal,opposite facing side walls 19.

To permit automatic assembly, the button 13 has an open bottom housing20 that allows the button 13 to be forcedly mounted on pin 18 from theoutside through said window 11 provided in the half-shell 7.

The pivoted button 13 is so shaped that its rear part 21 (with referenceto the appended figures), that is the part facing, toward the closed end8 of the shell 5, has a lower height than the front part 22, and issituated above an elastic tongue 23 of the support 4, said tongue beingable to bend in the plane of oscillation of the pivoted button 13.

The front end 22 of the button 13, on the other hand, has an inner orlower protrusion 24, at which a circular seat 25 is provided, open atthe bottom.

Said lower protrusion 24 of the pivoted button 13 is able to fit in aseat 26 provided on the inside of the lower half-shell 6 of the shell 5,when the blade is in a retracted position inside the shell, andtherefore forms a lock for the blade itself, preventing the blade fromemerging accidentally.

A circular open housing 25 provided below the button 13, on the otherhand, is such as to engage a transversal pin 27 provided in an opening28 in the lower half-shell 6 when the user voluntarily operates thebutton 13, thus forming a voluntary lock for the blade in conditions ofuse.

FIGS. 1 and 6 also show a further rear safety device for the blade, thatis able to prevent the blade from accidentally emerging if involuntarypressure is exerted on the rear part of the button 13, causingdisengagement of the protrusion 24 from the seat 26. This device, in theembodiment illustrated in FIGS. 1 to 4, comprises a slide 30, slidinglongitudinally in a guide bridge 31, and having at its front a covermember 32 able to be positioned on the back part of the pivoted button13 (see FIGS. 1 and 2), preventing any pressure on the button itself.Member 32 is advantageously higher than the guide bridge 31 for theslide 30, so that the safety device intervenes automatically when thescalpel is passed from hand to hand, should part of the user's hand bedirected towards the button 13.

A simpler solution, though with a lower degree of safety, consists inproviding a small projecting wall 35, shown schematically in FIGS. 5 and6, situated upstream of the window 11 and forming an obstacle for thefinger, such as to prevent contact with the button 13.

The scalpel according to the invention works as follows.

When the scalpel is not in use, the spring 15 holds the support 4 in aretracted position inside the shell 5, as shown in FIGS. 1 and 2. Inthis condition, the elastic tongue 23 pushes the back part 21 of thehorizontally pivoted button 13 upward, causing the front protrusion 24to enter the seat 26 provided in the half-shell 6, thus forming a lockfor the blade 3 in the retracted position, which prevents it fromaccidentally emerging. This lock is of the unintentional type, i.e. itintervenes automatically, irrespective of whether the user intends tooperate it.

Starting from the position shown in FIGS. 1 and 2, in order to use thescalpel it is first necessary to move the safety cover member backwards,with the thumb of one hand, if said safety member is in the activeposition, as shown in FIGS. 1 and 2. It is therefore sufficient to exerta light pressure on the rear part 21 of the pivoted button 13, with thesame thumb, and push the button 13 forwards, in the direction of theopen end 9 of the shell 5, so as to cause the blade 3 to emerge, asshown in FIGS. 3 and 4. In this condition, the scalpel is ready for use,without the blade being locked in this position, locking which takesplace only through a voluntary action on the part of the surgeon, aswill be seen with reference to FIGS. 5 and 6.

Remaining within the context of FIGS. 3 and 4, after use of theinstrument, simply releasing the button 13 causes the blade to returnautomatically inside the shell 5, through the action of return spring15, with consequent automatic locking, through engagement of theprotrusion 24 of the button 13 in the seat 26 of the half-shell 6.

Use of the scalpel shown in FIGS. 3 and 4, without locking of the blade,is suitable for that group of users that prefers automatic return of theblade 3 after use, without any manoeuvre having to be carried out. Analternative to use of the scalpel according to the invention is shown inFIGS. 5 and 6, in which locking of the blade has taken place, through avoluntary action on the part of the user, by means of engagement of thehousing 25 of the button 13 with the pin 27 provided in the half-shell6.

After use of the scalpel in the position shown in FIGS. 5 and 6,pressure must be exerted on the rear part 21 of the pivoted button 13,to cause unlocking of the blade and therefore its return inside theshell 5.

The shell 5, the support 4 and the pivoted button 13 are advantageouslymade of plastic whilst the spring 15 can be of plastic, metal, rubber orwith an air or gas system or the like.

It is also obvious that the blade 3 can have any shape, depending uponits use, without the characteristics of the scalpel according to theinvention undergoing any changes.

To aid voluntary locking of the blade in the position for use (FIGS. 5and 6) the horizontally hinged button 13 has a raised part 300 at thefront, which facilitates the lowering action to cause engagement of itshousing 25 with the pin 27.

FIGS. 7-9 show a different embodiment of the scalpel according to theinvention, which differs from that illustrated previously in that thetwo halves or half-shells 6, 7 of the shell 5, instead of beingassembled along a longitudinal plane, are assembled along a transversalplane. In this embodiment, the elements that are the same orcorresponding are marked with the same reference numbers as those usedin relation to FIGS. 1-6, and will not be further described. Inparticular, the support-slider 4 of the blade and the locking means forsaid support-slider by means of the pivoted button 13 remain unchanged.

Therefore, only the parts that differ from the preceding embodiment willbe described briefly below.

The half-shells 6 and 7, respectively, form a hollow body and a coveringcap of the shell 5, and are assembled together by means of seats 40 andflexible tongues 41, respectively.

Before the shell is closed, the support-slider 4 is inserted axiallyfrom the rear of the half-shell 6. At the back of the support-slider arod- or stem-shaped protrusion 45 is provided which is inserted in thehollow of the cap 7. Around the stem 45 a pressure spring 15 isarranged, between a widened terminal pin 16 of the stem 45, on one hand,and an inner abutment of the shell 5 in the assembled condition, on theother.

In FIGS. 7-9, an arched raised wall 35, similar to that shown in FIGS. 5and 6, has been indicated as an additional safety device againstunintentional operation of the button 13 (FIGS. 9, 9A, 9B). It isobvious, however, that the additional safety means can consist of thecover means shown in FIGS. 1-4.

We claim:
 1. A disposable surgical safety scalpel comprising a blade,fixed at one end to an elongated support, sliding longitudinally insidea protective shell, to bring said blade from a retracted inoperativeposition, in which it is housed inside said shell, to an exposedoperative position, through the action of an operator who acts on abutton of the support inserted in a window of said shell, an elasticreturn means to bring said blade back into the retracted inoperativeposition, said return means acting between said support and said shell,said button co-operating with said shell to provide automatic locking ofthe blade in said retracted inoperative position, wherein said button isa pivoted button, pivotally mounted on said support, having means thatcan be brought into engagement, upon a voluntary pressing action by theuser on said button, with a corresponding means provided in said shell,when said blade is in said exposed operative position, wherein saidmeans provided inside said pivoting button, is an open housing, and saidcorresponding means provided in said shell is a pin.
 2. A disposablesurgical safety scalpel comprising a blade, fixed at one end to anelongated support, sliding longitudinally inside a protective shell, tobring said blade from a retracted inoperative position, in which it ishoused inside said shell, to an exposed operative position, through theaction of an operator who acts on a button of the support inserted in awindow of said shell, an elastic return means to bring said blade backinto the retracted inoperative position, said return means actingbetween said support and said shell, said button co-operating with saidshell to provide automatic locking of the blade in said retractedinoperative position, wherein said button is a pivoted button, pivotallymounted on said support, having means that can be brought intoengagement, upon a voluntary pressing action by the user on said button,with a corresponding means provided in said shell, when said blade is insaid exposed operative position, wherein said pivoted button is pushedby an elastic tongue of the support against the inner wall of said shellopposite that having said window and said pivoted button has an innerprotrusion that engages with a corresponding seat made inside saidshell, under the action of said elastic tongue with said blade is insaid retracted inoperative position.
 3. A disposable surgical safetyscalpel comprising a blade, fixed at one end to an elongated support,sliding longitudinally inside a protective shell, to bring said bladefrom a retracted inoperative position, in which it is housed inside saidshell, to an exposed operative position, through the action of anoperator who acts on a button of the support inserted in a window ofsaid shell, an elastic return means to bring said blade back into theretracted inoperative position, said return means acting between saidsupport and said shell, said button co-operating with said shell toprovide automatic locking of the blade in said retracted inoperativeposition, wherein said button is a pivoted button, pivotally mounted onsaid support, having means that can be brought into engagement, upon avoluntary pressing action by the user on said button, with acorresponding means provided in said shell, when said blade is in saidexposed operative position, further comprising an additional safetymeans against accidental emergence of said blade, comprising a covermeans that can be brought, by means of a longitudinally sliding slide,to cover said pivoted button at least partly.
 4. A scalpel according toclaim 1 further comprising an additional safety means against accidentalemergence of said blade, comprising a cover means that can be brought,by means of a longitudinally sliding slide, to cover said pivoted buttonat least partly.
 5. A scalpel according to claim 2 further comprising anadditional safety means against accidental emergence of said blade,comprising a cover means that can be brought, by means of alongitudinally sliding slide, to cover said pivoted button at leastpartly.
 6. A scalpel according to claim 1, wherein a safety means isprovided against accidental operation of said pivoted button, consistingof a small raised wall situated upstream of said window of the case orsaid shell.
 7. A scalpel according to claim 1, wherein said shell ismade in two halves or half-shells assembled together.
 8. A scalpelaccording to claim 7, in which said half-shells are assembled along alongitudinal plane of said scalpel.
 9. A scalpel according to claim 7,in which said half-shells are assembled along a transversal plane ofsaid scalpel.